Samsung announces mass production of 4TB QLC-NAND SATA consumer SSD

Posted 07 August 2018 17:20 CET by Jan Willem Aldershoff

Samsung’s first QLC NAND SSD will have a capacity of 4TB, the exact name and price of the drive are still unknown. Performance and durability of the QLC NAND SSD should be similar to that of  TLC NAND based drives from the Korean electronics giant. The 4TB QLC NAND drive consists of 32 chips with 1Tbit 64-layer V-NAND.

Samsung is the biggest brand that won’t attend the Flash Memory Summit currently held in Santa Clara, California. Nevertheless, the Korean company today announced the start of mass production of its first QLC SSD. The timing is strikingly close to the opening day of the Flash Memory Summit.

QLC NAND (Quad Level Cell) stores 4 bits per cell, which means the controller needs to be able to distinguish between 16 different voltage levels, quite an achievement. QLC NAND has the drawback of being less durable than TLC memory which mainly means it can handle less program (write and delete) operations. Therefore, QLC NAND based SSDs are best suited for read intensive tasks.

Despite the drawbacks of QLC NAND, Samsung claims its QLC based SSD will be hardly less durable than its TLC (Triple Level Cell) based drives. Also, performance wise the QLC based drives should not be much slower than TLC based drives thanks to technology that Samsung calls TurboWrite. The company specifies sequential reads of 540 MB/s and sequential writes of 520 MB/s. With TurboWrite a part of the QLC NAND is used as buffer and treated like SLC  NAND (Single Level Cell), which means 1 bit per cell is used. Because only one bit per cell has to programmed, the buffer memory is much faster. All writes first pass the faster buffer memory and when the drive is idle, data is moved from the buffer to the regular QLC NAND cells.

Samsung has not disclosed any information the random reads and writes and the company also hasn’t published any durability numbers that should backup their claims. The QLC NAND based drives will be covered by a three-year warranty, less than that of the company’s 860 EVO and 860 PRO drives.

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